The present invention relates to a chemical mechanical polishing aqueous dispersion, a chemical mechanical polishing method, and a chemical mechanical polishing aqueous dispersion preparation kit.
A copper damascene interconnect provided in a high-performance LSI is formed by chemical mechanical polishing (hereinafter may be referred to as “CMP”). CMP includes a first polishing step of mainly polishing a copper film, and a second polishing step of polishing unnecessary copper, a barrier metal film, and an interlayer dielectric. In the first polishing step, (1) the copper film must be polished at a high speed without substantially polishing the barrier metal film formed of tantalum or titanium, and (2) surface defects (e.g., dishing and corrosion) of the copper film must be suppressed.
In recent years, the first polishing step has been desired to achieve improved flatness in order to deal with a reduction in line width (design rule). Therefore, the first polishing step may be divided into a bulk polishing step and a fine polishing step.
In the bulk polishing step, the deposited copper film is polished at a high speed until immediately before the barrier metal film is exposed. In the bulk polishing step, the copper film must be polished at a high speed while maintaining the flatness of the copper film. Moreover, corrosion and scratches of the copper film must be reduced as much as possible so that the subsequent fine polishing step is affected to a minimum extent.
In the fine polishing step, the copper film that remains unpolished in the bulk polishing step is polished until the barrier metal film is exposed. In the fine polishing step, the copper film must be polished while accurately maintaining the flatness of the copper film, and surface defects (e.g., dishing of the copper film and erosion of the interlayer dielectric) must be suppressed rather than polishing the copper film at a high speed.
A chemical mechanical polishing aqueous dispersion used in the bulk polishing step is desired to polish the copper film at a high speed. For example, JP-A-2005-268666 and JP-A-2006-080388 disclose polishing compositions that can polish the copper film at a high speed. However, when polishing a semiconductor having a minute wiring structure using the polishing composition disclosed in JP-A-2005-268666, the surface of the copper film may be roughened to a large extent, or scratches may occur to a large extent. On the other hand, since the polishing composition disclosed in JP-A-2006-080388 has a copper film polishing rate of 8000 angstroms/min or less, the polishing rate desired for the bulk polishing step cannot be achieved. As a result, the throughput decreases.
As described above, technology that can achieve a high copper film polishing rate desired for the bulk polishing step while forming an excellent polished surface has not been proposed. Therefore, development of a novel chemical mechanical polishing aqueous dispersion has been desired.